/*
 * OF helpers for IOMMU
 *
 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <linux/export.h>
#include <linux/iommu.h>
#include <linux/limits.h>
#include <linux/of.h>
#include <linux/of_iommu.h>
#include <linux/of_pci.h>
#include <linux/slab.h>

#define NO_IOMMU        1

static const struct of_device_id __iommu_of_table_sentinel
        __used __section(__iommu_of_table_end);

/**
 * of_get_dma_window - Parse *dma-window property and returns 0 if found.
 *
 * @dn: device node
 * @prefix: prefix for property name if any
 * @index: index to start to parse
 * @busno: Returns busno if supported. Otherwise pass NULL
 * @addr: Returns address that DMA starts
 * @size: Returns the range that DMA can handle
 *
 * This supports different formats flexibly. "prefix" can be
 * configured if any. "busno" and "index" are optionally
 * specified. Set 0(or NULL) if not used.
 */
int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
                      unsigned long *busno, dma_addr_t *addr, size_t *size)
{
        const __be32 *dma_window, *end;
        int bytes, cur_index = 0;
        char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];

        if (!dn || !addr || !size)
                return -EINVAL;

        if (!prefix)
                prefix = "";

        snprintf(propname, sizeof(propname), "%sdma-window", prefix);
        snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
        snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);

        dma_window = of_get_property(dn, propname, &bytes);
        if (!dma_window)
                return -ENODEV;
        end = dma_window + bytes / sizeof(*dma_window);

        while (dma_window < end) {
                u32 cells;
                const void *prop;

                /* busno is one cell if supported */
                if (busno)
                        *busno = be32_to_cpup(dma_window++);

                prop = of_get_property(dn, addrname, NULL);
                if (!prop)
                        prop = of_get_property(dn, "#address-cells", NULL);

                cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
                if (!cells)
                        return -EINVAL;
                *addr = of_read_number(dma_window, cells);
                dma_window += cells;

                prop = of_get_property(dn, sizename, NULL);
                cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
                if (!cells)
                        return -EINVAL;
                *size = of_read_number(dma_window, cells);
                dma_window += cells;

                if (cur_index++ == index)
                        break;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(of_get_dma_window);

static bool of_iommu_driver_present(struct device_node *np)
{
        /*
         * If the IOMMU still isn't ready by the time we reach init, assume
         * it never will be. We don't want to defer indefinitely, nor attempt
         * to dereference __iommu_of_table after it's been freed.
         */
        if (system_state >= SYSTEM_RUNNING)
                return false;

        return of_match_node(&__iommu_of_table, np);
}

static int of_iommu_xlate(struct device *dev,
                          struct of_phandle_args *iommu_spec)
{
        const struct iommu_ops *ops;
        struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
        int err;

        ops = iommu_ops_from_fwnode(fwnode);
        if ((ops && !ops->of_xlate) ||
            !of_device_is_available(iommu_spec->np) ||
            (!ops && !of_iommu_driver_present(iommu_spec->np)))
                return NO_IOMMU;

        err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
        if (err)
                return err;
        /*
         * The otherwise-empty fwspec handily serves to indicate the specific
         * IOMMU device we're waiting for, which will be useful if we ever get
         * a proper probe-ordering dependency mechanism in future.
         */
        if (!ops)
                return -EPROBE_DEFER;

        return ops->of_xlate(dev, iommu_spec);
}

struct of_pci_iommu_alias_info {
        struct device *dev;
        struct device_node *np;
};

static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
{
        struct of_pci_iommu_alias_info *info = data;
        struct of_phandle_args iommu_spec = { .args_count = 1 };
        int err;

        err = of_pci_map_rid(info->np, alias, "iommu-map",
                             "iommu-map-mask", &iommu_spec.np,
                             iommu_spec.args);
        if (err)
                return err == -ENODEV ? NO_IOMMU : err;

        err = of_iommu_xlate(info->dev, &iommu_spec);
        of_node_put(iommu_spec.np);
        return err;
}

const struct iommu_ops *of_iommu_configure(struct device *dev,
                                           struct device_node *master_np)
{
        const struct iommu_ops *ops = NULL;
        struct iommu_fwspec *fwspec = dev->iommu_fwspec;
        int err = NO_IOMMU;

        if (!master_np)
                return NULL;

        if (fwspec) {
                if (fwspec->ops)
                        return fwspec->ops;

                /* In the deferred case, start again from scratch */
                iommu_fwspec_free(dev);
        }

        /*
         * We don't currently walk up the tree looking for a parent IOMMU.
         * See the `Notes:' section of
         * Documentation/devicetree/bindings/iommu/iommu.txt
         */
        if (dev_is_pci(dev)) {
                struct of_pci_iommu_alias_info info = {
                        .dev = dev,
                        .np = master_np,
                };

                err = pci_for_each_dma_alias(to_pci_dev(dev),
                                             of_pci_iommu_init, &info);
        } else {
                struct of_phandle_args iommu_spec;
                int idx = 0;

                while (!of_parse_phandle_with_args(master_np, "iommus",
                                                   "#iommu-cells",
                                                   idx, &iommu_spec)) {
                        err = of_iommu_xlate(dev, &iommu_spec);
                        of_node_put(iommu_spec.np);
                        idx++;
                        if (err)
                                break;
                }
        }

        /*
         * Two success conditions can be represented by non-negative err here:
         * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
         *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
         * <0 : any actual error
         */
        if (!err)
                ops = dev->iommu_fwspec->ops;
        /*
         * If we have reason to believe the IOMMU driver missed the initial
         * add_device callback for dev, replay it to get things in order.
         */
        if (ops && ops->add_device && dev->bus && !dev->iommu_group)
                err = ops->add_device(dev);

        /* Ignore all other errors apart from EPROBE_DEFER */
        if (err == -EPROBE_DEFER) {
                ops = ERR_PTR(err);
        } else if (err < 0) {
                dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
                ops = NULL;
        }

        return ops;
}